Bangalore: A local Congress leader has served a legal notice to Gujarat Chief Minister Narendra Modi asking him to apologise and withdraw his remarks calling Prime Minister Manmohan Singh a "night watchman" of Gandhi family.

"Modi should do it (apologise or withdraw remarks) within three days of receipt of the notice... failing which I will file a private complaint against him before Chief Metropolitan Magistrate for offence of defamation," KK Benson, a former Pradesh Congress Member, said.

In the legal notice released to the media here, Benson said by calling Singh night watchman, Modi has "insulted, degraded and defamed" in public the image and good reputation of Prime Minister's post.

Without naming Manmohan Singh, Modi on March 3 had said the Congress appointed a "night watchman" to keep the seat warm for the first family of the Congress. "They did not realise that the night will be so long and dark. As a buffer, they appointed an economist to the post," he said.